Automatic regulation of turbine generators to relieve power-supply systems of steel-mill load swings

Certain steel-mill loads are fast, cyclic, and of considerable magnitude. Given a set of conditions involving such a load, a relatively small steel mill, speed-controlled generating capacity all connected to a large power-supply system, much of the swings in the steel-mill load will be taken by the large supply system. Of itself, this result may not assume special importance. When transmissions in the large power-supply system, well-loaded under steady-state conditions, are involved, and speed governing of the system is at the remote end of the transmissions, the cyclic loads tend to reappear in the transmissions. These circuits may, according to their finite transmitting abilities and the swing peaks imposed on them, be unable to carry the peaks without undesirable voltage depressions or cause undesirable frequency variations on the system. Generation of power from by-product fuels in a steel mill is generally economical but is dependent on the continuity and quality of the nonstorable fuel as well as on the steaming and generating capacity installed. Relief to a large power-supply system from the cyclic load swings normally carried by that supply system has been made possible by a new static load control and hydraulic servomotor to cause the steel-mill turbine generators to respond to the regulator. The combination has been applied successfully to two 20,000-kw turbine generators, causing one or both to take a base load, a percentage of the variable load, and to modify their total loads according to available steam pressure. The turbine-generator response can be as high as 5,000 kw per second on each unit. High-speed charts show the loads on the various circuits with and without the load control in operation.